I have a 1987 5.7 TBI Iroc and am having issues with the cold start valve. I understand that I can convert to an 1989 ecm or prom and block off the CSV. Not sure what I would need to buy.

Need to buy:

EMC?
Prom?
Both?

appreciate any help on this.

 

You can unplug the electrical connection on the cold start timer switch or ninth injector but its best to go on ebay and buy a lock off kit there around $30 just to make sure the injector doesn't leak into the intake. If you want your memcal reprogramed send me a personal message I can assist the change.
the ecm is the same the programing is the change. 89 has vats so the vats will need to be disabled. The ac fan switch type is different between 86-88 so that will need to be changed to normally closed in the programing other wise the fans will run all the time.